Yes, you CAN be too fit for your own good: Why exercise may be harmful to the heart

BBC presenter Andrew Marr’s stroke has caused surprise not just because of his age — he is only 53 — but also because, as a keen long-distance runner, he is so fit.

But surprising new evidence suggests that exercise may not always protect you against ill health – and may even be harmful to the hearts of some people.

A study just published in the journal PLoS One analysed data from six exercise studies involving 1,687 regular exercisers to find out the effects of —regular workouts on the heart.

The results shocked and confused the
scientists: in almost one in ten people tested, exercise seemed
adversely to affect blood pressure, insulin levels or ‘good’ HDL
cholesterol levels.

And
in seven per cent of people, not just one but two of these risk factors
for heart disease were worse as a result of exercise.

There
is no clear explanation for this effect on a small portion of the
population, but ‘it’s not a good sign,’ says Claude Bouchard, the
study’s lead author and a professor of genetics and nutrition at
Louisiana State University.

He
suspects it is down to genetics and advises exercisers to have their
blood pressure, cholesterol and glucose checked regularly.

Regular
amounts of aerobic exercise, such as running, are known to slow the
unhealthy changes to the cardiovascular system that occur with age.

However,
intense and prolonged endurance training for many years — for instance,
for marathons or triathlons — could be damaging to the heart, an
editorial review published last year in the British Journal of Sports
Medicine suggested.

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The author, Greg Whyte, professor of sports science at Liverpool John Moores University, explains: ‘Our research found that 50 per cent of long-term endurance and ultra-endurance runners, some of whom had been training for 43 years, showed signs of heart damage.

‘It is well documented that among veteran athletes there is a higher incidence of early symptoms of cardiac disease, which might increase the risk of a heart attack.

'There is a build-up of collagen in place of heart muscle, and compounds of blood markers that can make someone more susceptible to unusual heart rhythms.

‘It does not occur in people who just do a few marathons during their lifetime, but is a risk in people who have been training long and hard for years.’

Recovering from a stroke: Andrew Marr is a keen long-distance runner

So, should you be worried about doing exercise?

No, says Professor Whyte, pointing to overwhelming evidence that ‘exercise is wholly beneficial’, not just for the heart but for the whole body.

Even in Bouchard’s study, it was not all bad news.

For 10 per cent of people there were enormous gains in at least one measure of heart disease risk, with some improving by up to 50 per cent.

And among those who did have adverse outcomes, there was no evidence that these led to heart attacks or other health problems.

Professor Whyte says: ‘There will always be a few cases of people with underlying health problems and heart issues for whom physical activity can be problematic, but most people should be doing more of it, not less.’

Even ageing long-distance racers should not necessarily hang up their trainers.

‘They may need to be monitored, but the benefits for the heart still outweigh any risks.,’ says Professor Whyte

As for the risk of stroke, most studies say exercise is beneficial for stroke prevention in healthy people, says John Brewer, professor of sport at the University of Bedfordshire.

‘It’s wise to get a check-up if you haven’t exercised for a while or have a family history of heart attacks and strokes, but in general, the evidence suggests that everything from moderate activity to higher-intensity and longer-duration exercise are beneficial.’